Redundancy power supplying is common means for protecting a working machine from possible damages caused by unstable power while allowing the machine to keep on working. When main power supplying is suspended, redundancy power supplying can take over the main power supplying immediately in order not to interrupt power supplying. With the redundancy power supplying, buffering time enough for a working machine or an operational process to react properly can be acquired. Damages due to power interruption can thus be avoided.
Currently available power supply systems have some drawbacks. For example, since an Oring diode is generally used in an output stage of a redundancy power supply, the main power supply cannot take the priority to supply power when the voltage of the redundancy power supply is higher or equal to that of the main power supply. Even though the main power supply in some power supply system is allowed to supply power as a priority, the power supply system still suffer from either low efficiency or large power voltage fluctuation while switching between the main power supply and the redundancy power supply. Moreover, the control mechanisms of the prior art systems are complicated and thus might slow down the response rate of the power supply system. The redundancy power supplying performance is unsatisfactory.